Commercial buildings use Foamglas cellular glass insulation where ordinary foam boards fall short. It’s made of glass blown into tiny sealed bubbles, so it won’t burn, won’t soak up water and blocks water vapor completely. It’s also strong enough to sit under concrete slabs and heavy roof decks. The trade-off is a modest R-value, about …

Double bubble insulation does work on metal buildings, but only in a narrow way. It needs an open air gap next to its foil face, and its main jobs are blocking summer sun heat and stopping condensation from dripping off the steel. Pressed flat against metal with no air space, it adds very little R-value. …

A Denver library needs relative humidity held between 30 and 50 percent for general book collections, with temperature at or below 70 degrees Fahrenheit. That number matters less than what happens around it, though. A room that swings from 35 to 55 percent humidity every week damages a collection faster than a room that sits …